In the biotechnological production Of L-lysine and L-glutamate by Corynebacterium glutamicum media based on glucose, fructose or sucrose are typically used. Glutamate production by C glutamicum ATCC13032 was very similar on glucose, fructose, glucose plus fructose and sucrose. In contrast, lysine production of genetically defined C glutamicum strains was significantly higher on glucose than on the other carbon sources. To test whether malic enzyme or fructose-1,6-bisphosphatase might limit growth and lysine on fructose, glucose plus fructose or sucrose, strains overexpressing either malE which encodes the NADPH-dependent malic enzyme or the fructose-1,6-bisphosphatase gene fbp were generated. Overexpression of malE did not improve lysine production on any of the tested carbon sources. Upon overexpression of fbp lysine yields on glucose and/or fructose were unchanged, but the lysine yield on sucrose increased twofold. Thus, fructose-1,6-bisphosphatase was identified as a limiting factor for lysine production by C glutamicum with sucrose as the carbon source. (c) 2005 Elsevier Inc. All rights reserved.